Silicone composite particle and a method for preparing the same

ABSTRACT

The purpose of the present invention is to provide a silicone rubber particle having a higher light scattering property which can be expected to provide makeup cosmetics such as a foundation with a higher soft focus effect, and a method for preparing the same. The present invention provides a silicone composite particle composed of a silicone rubber particle and a polyorganosilsesquioxane, wherein the silicone rubber particle has plural dents on its surface and said polyorganosilsesquioxane adheres to the surface of the silicone rubber particle. Further, the present invention provides a method for preparing the silicone composite particle, wherein the method includes steps of subjecting organotrialkoxysilane to a hydrolysis and subsequent condensation in the presence of water, an alkaline substance and a silicone rubber particle containing therein a liquid to thereby have a resultant polyorganosilsesquioxane adhered to the surface of the silicone rubber particle, and subsequently removing the liquid.

CROSS REFERENCE

This application claims the benefits of Japanese Patent application No.2013-094146 filed on Apr. 26, 2013, the contents of which areincorporated by reference.

The present invention relates to a silicone composite particle and amethod for preparing the same.

BACKGROUND OF THE INVENTION

Various spherical silicone particles have been used in order to providea non-sticky or smooth feeling or extensibility to cosmetics. Forinstance, Japanese Patent Application Laid-Open No. Sho63-297313describes cosmetics containing polymethylsilsesquioxane powder, JapanesePatent Application Laid-Open No. H08-12524 describes makeup cosmeticscontaining spherical silicone rubber powder and Japanese PatentApplication Laid-Open No. H09-20631 describes cosmetics containingcomposite silicone powder composed of spherical silicone rubbermicroparticles covered with a polyorganosilsesquioxane resin. Thesesilicone rubber particles and the particle composed of sphericalsilicone rubber microparticles covered with a polyorganosilsesquioxaneresin provide a soft feeling, in addition to the aforesaid feeling, tocosmetics.

Makeup cosmetics such as a foundation, containing silicone particlesprovide an effect of natural finish without artificial gloss, i.e. softfocus effect, to cosmetics. For instance, in the cosmetics obtained inthe method described in Japanese Patent Application Laid-Open No.H09-2063, the polyorganosilsesquioxane covering the silicone particleshas a particle diameter of approximately 100 nm. Thepolyorganosilsesquioxane also scatters light to provide a high softfocus effect to cosmetics.

Further, it is known to provide many convexes or concaves on a surfaceof silicone particles or making a shape of silicone particlesnon-spherical to improve a light scattering property. Japanese PatentApplication Laid-Open No. 2004-359592 describes sphericalpolyorganosilsesquioxane particles having a projection on its surface.Japanese Patent Application Laid-Open No. 2000-191788 describesspherical organosilicone microparticles having many dents on itssurface. Japanese Patent Application Laid-Open No. 2011-1537 describesorganosilicone microparticles having a hollow spindle shape with pluralconcaves on its surface. Japanese Patent Application Laid-Open No.2011-57785 describes deformed organosilicone microparticles having ahexahedron or polyhedron shape with each face being concave. WO2011/074066 describes organosilicone microparticles which are sphericalas a whole, and have, on its surface, plural indefinite faces and aprotruded network structure surrounding the indefinite faces. WO2011/111179 describes organosilicone microparticles which aretetrahedral as a whole and have concaves with a generally circularperiphery on each face of the tetrahedron.

PRIOR LITERATURES Patent Literatures

-   [Patent Literature 1] Japanese Patent Application Laid-Open No.    Sho63-297313-   [Patent Literature 2] Japanese Patent Application Laid-Open No.    H08-12524-   [Patent Literature 3] Japanese Patent Application Laid-Open No.    H09-20631-   [Patent Literature 4] Japanese Patent Application Laid-Open No.    2004-359592-   [Patent Literature 5] Japanese Patent Application Laid-Open No.    2000-191788-   [Patent Literature 6] Japanese Patent Application Laid-Open No.    2011-1537-   [Patent Literature 7] Japanese Patent Application Laid-Open No.    2011-57785-   [Patent Literature 8] WO 2011/074066-   [Patent Literature 9] WO 2011/111179

SUMMARY OF THE INVENTION

However, the aforesaid polyorganosilsesquioxane particles and organicsilicone microparticles are resinous hard materials and, therefore,cannot provide soft feeling to cosmetics. In recent years, it isbecoming important that makeup cosmetics such as foundations provideinartificial natural finish, i.e. bare skin-like feeling. Therefore, itis desired to provide a higher light scattering effect by siliconerubber particles.

One of the purposes of the present invention is to provide a siliconerubber particle having a higher light scattering property which particleis expected to provide makeup cosmetics such as foundations with ahigher soft focus effect, and a method for preparing the same.

The present inventors have made research and found a novel siliconecomposite particle composed of a silicone rubber particle having pluraldents on its surface and a polyorganosilsesquioxane which adheres to thesurface of the silicone rubber particle, and a method for preparing thesame.

Thus, the present invention provides a silicone composite particlecomposed of a silicone rubber particle and a polyorganosilsesquioxane,wherein the silicone rubber particle has plural dents on its surface andsaid polyorganosilsesquioxane adheres to the surface of the siliconerubber particle.

Further, the present invention provides a method for preparing thesilicone composite particle comprising steps of subjectingorganotrialkoxysilane to hydrolysis and condensation reactions in thepresence of water, an alkaline substance, and a silicone rubber particlecontaining therein a liquid to thereby have a resultantpolyorganosilsesquioxane adhered to the surface of the silicone rubberparticle, and subsequently removing the liquid.

The present silicone composite particle is expected to have a higherlight scattering effect.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is an electron microscope image of a surface of the siliconecomposite particle obtained in Example 1.

FIG. 2 is an electron microscope image of a surface of the siliconecomposite particle obtained in Example 2.

FIG. 3 is an electron microscope image of a surface of the siliconecomposite particle obtained in Comparative Example 1.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described below in detail.

[Silicone Composite Particle]

The present invention provides a silicone composite particle composed ofa silicone rubber particle and polyorganosilsesquioxane. The presentinvention is characteristic in that the silicone rubber particle hasplural dents on its surface and the polyorganosilsesquioxane adheres tothe surface of the silicone rubber particle.

Silicone Rubber Particle

The silicone rubber particle preferably has a volume-average particlediameter of 0.5 to 100 μm, more preferably 1 to 40 μm. If thevolume-average particle diameter is less than the aforesaid lower limit,the silicone composite particles obtained have a higher tendency foragglomeration. It is not easy to disperse the agglomerated particlesinto primary particles. Further, the agglomerated particles givecosmetics a less non-sticky feeling. If the volume-average particlediameter is larger than the aforesaid upper limit, non-sticky feelingand smoothness of cosmetics decrease and rough feeling appears. A methodfor determining the volume-average particle diameter is selecteddepending on a particle diameter of the silicone composite particle.When the particle diameter is 1 μm or more, an electric resistancemethod is used. When the particle diameter is less than 1 μm, a laserdiffraction-scattering method is used.

The silicone rubber particle has plural dents on its surface. The shapeof the dent may be any of a part of spherical surface and a polyhedron.In the present method described below, polyhedral dents are mostlyformed, rather than dents of a part of spherical surface. The polyhedronhere may be a convex polyhedron whose all interior angles are less than180 degrees or a concave polyhedron whose at least one interior angle islarger than 180 degrees. The number of the dents is at least two,preferably three or more, per silicone rubber particle. If the number ofdents is less than two, a high light scattering effect is not expected.The upper limit of the number of the dents is not limited to anyparticular one, but generally depends on a size of the silicone rubberparticle and a longest diameter of the dent. The longest diameter of thedent is preferably 100 nm or more, more preferably 200 nm or more. Ifthe longest diameter is shorter than 100 nm, a higher light scatteringeffect is not expected. The upper limit of the longest diameter dependson a surface area of the silicone rubber particle, but is not limited toany particular one. When the silicone rubber particle has more dents onits surface, the longest diameter of the dent tends to be shorter andthe shape of the silicone rubber particle is nearly spherical. When thesilicone rubber particle has a fewer dents on its surface, the longestdiameter of the dent tend to be longer and the silicone rubber particleis mostly of a indefinite shape. The shape of the present siliconerubber particle can be confirmed by observation with an opticalmicroscope or an electron microscope. The shape, the number and thelongest diameter of the dents on the particle surface can be confirmedby observation with an electron microscope.

The silicone rubber which constitutes the silicone rubber particle ispreferably non-sticky and has a rubber hardness of 5 to 35, morepreferably 10 to 30, as determined with a Type A durometer in accordancewith the Japanese Industrial Standards (JIS) K 6253. If the rubberhardness is less than the aforesaid lower limit, the silicone compositeparticles obtained has a tendency for agglomeration and do not easilydisperse to become primary particles and, further, a non-sticky feelingof cosmetics decreases. If the rubber hardness is larger than theaforesaid upper limit, a silicone composite particle having dents cannotbe obtained in the present method described below.

The silicone rubber is particularly a cured product having a linearorganosiloxane block represented by the formula —(R¹ ₂SiO_(2/2))_(n)—,wherein R¹ is an unsubstituted or substituted monovalent hydrocarbongroup having 1 to 30 carbon atoms and n is a positive integer of from 5to 5,000.

Examples of R¹ include an alkyl group such as a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group, a hexyl group, aheptyl group, an octyl group, a decyl group, an undecyl group, a dodecylgroup, a tetradecyl group, a pentadecyl group, a hexadecyl group, aheptadecyl group, an octadecyl group, a nonadecyl group, an eicosylgroup, a henicosyl group, a docosyl group, a tricosyl group, a tetracylgroup, and a triacontyl group; an aryl group such as a phenyl group, atolyl group, and a naphthyl group; an aralkyl group such as a benzylgroup and a phenethyl group; an alkenyl group such as a vinyl group andan allyl group; a cycloalkyl group such as a cyclopentyl group, acyclohexyl group, and a cycloheptyl group; and those hydrocarbon groupswherein a part or all of the hydrogen atoms bonded to a carbon atom ofthese groups is substituted with a substituent as a halogen atom such asa fluorine atom, a chlorine atom, a bromine atom and an iodine atomand/or an amino group, an acryloyloxy group, a methacryloyloxy group, anepoxy group, glycidoxy group, a mercapto group and a carboxyl group.

The silicone rubber particle is obtained by curing a curable liquidsilicone composition, for instance, by a condensation reaction of acompound having a methoxy silyl group (≡SiOCH₃) and a compound having ahydroxy silyl group (≡SiOH), a radical reaction of a compound having amercaptopropyl silyl group (≡Si—C₃H₆SH) and a compound having a vinylsilyl group (≡SiCH═CH₂), or an addition reaction of a compound having avinyl silyl group (≡SiCH═CH₂) and a compound having a hydrosilyl group(≡SiH). Among these reactions, the addition reaction is preferable inview of reactivity.

In a case where the silicone rubber particle is prepared by the additionreaction, a liquid silicone composition comprising a combination of anorganopolysiloxane having monovalent olefinic unsaturated groups and anorganohydrogen polysiloxane may be subjected to an addition reaction inthe presence of a platinum group metal catalyst, wherein theorganopolysiloxane is represented by an average formula: R² _(a)R³ _(b)SiO_((4-a-b)/2) and having at least two monovalent olefinic unsaturatedgroups per molecule and the organohydrogen polysiloxane is representedby an average formula: R⁴ _(c)H_(d)SiO_((4-c-d)/2) and having at leastthree hydrogen atoms each bonded to a silicone atom per molecule; or theorganopolysiloxane is represented by an average formula: R² _(a)R³_(b)SiO_((4-a-b)/2) and having at least three monovalent olefinicunsaturated groups per molecule and the organohydrogen polysiloxane isrepresented by an average formula: R⁴ _(c)H_(d)SiO_((4-c-d)/2) andhaving at least two hydrogen atoms each bonded to a silicon atom permolecule; wherein a ratio of the organopolysiloxane having monovalentolefinic unsaturated groups to the organohydrogen polysiloxane is suchthat the number of the hydrosilyl group is 0.5 to 2, per the number ofthe monovalent olefinic unsaturated group.

In the aforesaid formula, R² is an unsubstituted or substitutedmonovalent hydrocarbon group having 1 to 30 carbon atoms but is not analiphatic unsaturated group. R³ is a monovalent olefinic unsaturatedgroup, for instance, an alkenyl group having 2 to 6 carbon atoms. “a”and “b” are positive numbers satisfying the equations, 0<a<3, 0<b<=3 and0.1<=a+b<=3, preferably 0<a<=2.295, 0.005<=b<=2.3 and 0.5<=a+b<=2.3. R⁴is an unsubstituted or substituted monovalent hydrocarbon group having 1to 30 carbon atoms but is not an aliphatic unsaturated group. “c” and“d” are positive numbers satisfying the equations, 0<c<3, 0<d<=3 and0.1<=c+d<=3, preferably 0<c<=2.295, 0.005<=d<=2.3 and 0.5<=c+d<=2.3.

Examples of R² include an alkyl group such as a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group, a hexyl group, aheptyl group, an octyl group, a decyl group, an undecyl group, a dodecylgroup, a tetradecyl group, a pentadecyl group, a hexadecyl group, aheptadecyl group, an octadecyl group, a nonadecyl group, an eicosylgroup, a henicosyl group, a docosyl group, a tricosyl group, a tetracylgroup and a triacontyl group; an aryl group such as a phenyl group, atolyl group and a naphthyl group; an aralkyl group such as a benzylgroup and a phenethyl group; a cycloalkyl group such as a cyclopentylgroup, a cyclohexyl group and a cycloheptyl group; and those hydrocarbongroups wherein a part or all of the hydrogen atoms bonded to a carbonatom of these groups is substituted with a substituent such as a halogenatom such as a fluorine atom, a chlorine atom, a bromine atom and aniodine atom and/or an amino group, an acryloyloxy group, amethacryloyloxy group, an epoxy group, a glycidoxy group and a carboxylgroup. Particularly, it is industrially preferable that 50 mole % ormore of R² are a methyl group.

Examples of R³ include a vinyl group, an allyl group, a propenyl group,a butenyl group, a pentenyl group and a hexenyl group. Particularly, avinyl group is industrially preferable.

Examples of R⁴ include the same groups as those described above for R².

The organopolysiloxane and the organohydrogenpolysiloxane preferablyhave a viscosity at 25 degrees C. of 100,000 mm²/s or less, morepreferably 10,000 mm²/s or less. If the viscosity is higher than theaforesaid upper limit, it is difficult to obtain a particle having anarrow molecular weight range in the present method described below. Theorganopolysiloxane and the organohydrogenpolysiloxane may be a linear,cyclic or branched structure. Particularly, a linear structure ispreferable. The viscosity in the present invention is determined at 25degrees C. with an Ostwald viscometer.

For preparing the present silicone rubber particle, it is preferable, asmentioned above, that the liquid curable silicone composition comprisesa combination of an organopolysiloxane having at least two monovalentolefinic unsaturated groups per molecule and anorganohydrogenpolysiloxane having at least three hydrogen atoms eachbonded to a silicon atom per molecule, or a combination of anorganopolysiloxane having at least three monovalent olefinic unsaturatedgroups per molecule and an organohydrogenpolysiloxane having at leasttwo hydrogen atoms each bonded to a silicon atom per molecule. If thecombination of the polysiloxanes is not as mentioned above, a curedrubber tends to be sticky.

The platinum group metal catalyst may be a well-known or known catalystfor hydrosilylation. Examples of the catalyst include an element ofplatinum group metals such as platinum, including platinum black,rhodium and palladium; platinum chloride such as H₂PtCl₄.kH₂O,H₂PtCl₆.kH₂O, NaHPtCl₆.kH₂O, KHPtCl₆.kH₂O, Na₂PtCl₆.kH₂O, K₂PtCl₄.kH₂O,PtCl₄.kH₂O, PtCl₂, and Na₂HPtCl₄.kH₂O, wherein “k” is an integer of 0 to6, preferably 0 or 6; a chloroplatinic acid and a chloroplatinate; analcohol-modified chloroplatinic acid (see U.S. Pat. No. 3,220,972); acomplex of chloroplatinic acid with an olefin (see U.S. Pat. No.3,159,601, U.S. Pat. No. 3,159,662, and U.S. Pat. No. 3,775,452); aplatinum group metal, such as platinum black and palladium, supported ona carrier such as alumina, silica and carbon; a rhodium-olefin complex;chlorotris(triphenylphosphine) rhodium (Wilkinson catalyst); and acomplex of platinum chloride, chloroplatinic acid or chloroplatinatewith siloxane having a vinyl group, in particular vinyl group-containingcyclic siloxane.

The amount of the platinum group metal catalyst may be an effectiveamount as a hydrosilylation catalyst. The amount of the catalyst isusually such that the amount of the platinum group metal in the catalystis about 0.1 to about 500 ppm by mass, preferably about 0.5 to about 200ppm by mass, more preferably about 1 to about 100 ppm by mass, relativeto a total mass of the curable liquid silicone composition.

The silicone rubber particle may contain a silicone oil, inorganicpowder and organic powder.

Polyorganosilsesquioxane

In the present invention, the polyorganosilsesquioxane is preferablyparticulate. The particle diameter is 10 to 400 nm, preferably 50 to 200nm. If the particle diameter is smaller than the aforesaid lower limit,the light scattering effect of the silicone composite particle tends todecrease. If the particle diameter is larger than the aforesaid upperlimit, soft feeling of cosmetics and a light scattering effect of thesilicone composite particle tend to decrease. Further, if the particlediameter is too large, there is a tendency that dents are not formed onthe surface of the particle. The particle diameter of thepolyorganosilsesquioxane should be smaller than that of the aforesaidsilicone rubber particle. The polyorganosilsesquiocane particles mayattach to the surface of the silicone rubber particle in a scatteredstate or in a dense state. Higher dense state is preferable because manydents are easily formed. The shape of the polyorganosilsesquioxaneparticles is not limited, but preferably almost spherical orhemispherical. The diameter and shape of the polyorganosilsesquioxaneparticles and density on the particle surface may be confirmed byobserving the silicone composite particle with an electron microscope.

The amount of the polyorganosilsesquioxane adhered on the surface of thesilicone rubber particle is preferably 1 to 50 parts by mass, morepreferably 2 to 25 parts by mass, per 100 parts by mass of the siliconerubber particles. If the amount is smaller than the aforesaid lowerlimit, the light scattering effect of the silicone composite particlesand the non-sticky feeling of cosmetics decrease and, further, there isa tendency that dents are not formed on the surface of the siliconerubber particle. If the amount is larger than the aforesaid upper limit,a soft feeling of cosmetics decreases.

The polyorganosilsesquioxane is a resinous solid composed ofthree-dimensionally crosslinked units represented by, for instance, aformula, R⁵SiO_(3/2), to form a network, wherein R⁵ is an unsubstitutedor substituted monovalent hydrocarbon group having 1 to 20 carbon atoms.Examples of R⁵ include an alkyl group such as a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group, a hexyl group, aheptyl group, an octyl group, a decyl group, a undecyl group, a dodecylgroup, a tetradecyl group, a pentadecyl group, a hexadecyl group, aheptadecyl group, an octadecyl group, a nonadecyl group and an eicosylgroup; an alkenyl group such as a vinyl group and an allyl group; anaryl group such as a phenyl group, a tolyl group and a naphthyl group;an aralkyl group such as a benzyl group and a phenethyl group; acycloalkyl group such as a cyclopentyl group, a cyclohexyl group and acycloheptyl group; and those hydrocarbon groups wherein a part or all ofthe hydrogen atoms bonded to a carbon atom of these groups issubstituted with a substituent such as a halogen atom such as a fluorineatom, a chlorine atom, a bromine atom and an iodine atom and/or an aminogroup, an acryloyloxy group, a methacryloyloxy group, an epoxy group, aglycidoxy group, a mercapto group, and a carboxyl group. For thepolyorganosilsesquioxane to adhere to the surface of the silicone rubberparticle, 50 mole % or more, more preferably 80 mole % or more, furtherpreferably 90 mole % or more, of R⁵ is preferably a methyl group, avinyl group or a phenyl group.

The polyorganosilsesquioxane may contain, in addition to R⁵SiO_(3/2)unit, one or more units represented by R⁵ ₂SiO_(2/2), R⁵ ₃SiO_(1/2) orSiO_(4/2), as long as non-aggregability and dispersibility of thesilicone composite particle and feeling such as non-sticky, smooth andsoft feeling of cosmetics are not lost. In thispolyorganosilsesquioxane, the amount of the R⁵SiO_(3/2) unit ispreferably 70 to 100 mole %, more preferably 80 to 100 mole %, relativeto the whole siloxane units.

[Preparation of a Silicone Composite Particle]

The present invention further provides a method for preparing theafore-mentioned silicone composite particle. The present methodcomprises a step (i): an organotrialkoxysilane is subjected tohydrolysis and condensation reactions in the presence of water, analkaline substance and a silicone rubber particle containing therein aliquid; and a step (ii): the liquid is subsequently removed. Until thestep of adhering polyorganosilsesquioxane on the surface of the siliconerubber particle, i.e. the aforesaid step (i), the silicone compositeparticle have no dent on its surface. In the step of removing theliquid, i.e. the aforesaid step (ii), the silicone rubber particleshrinks and, thereby, dents appear on the surface.

The present method will be described below in detail.

(0) Preparation of a Silicone Rubber Spherical Particle Containing aLiquid

The silicone rubber spherical particle containing a liquid may beprepared according to any conventional manners. For instance, it can beprepared in a state of an aqueous dispersion of the silicone rubberparticle containing silicone oil. The aqueous dispersion may beprepared, for instance, in a manner where an intended liquid isdissolved in the aforesaid curable liquid silicone composition, to whicha surfactant and water are added, emulsified to prepare an emulsion,subsequently a catalyst is added thereto and, then, a curing reaction isconducted. The present method may comprise a step of having a liquidcontained to a silicone rubber particle, before the aforesaid step (i).

The liquid to be contained in the silicone rubber particle needs to besoluble in the curable liquid silicone composition and to be unreactivewith the curable liquid silicone composition. The liquid is notparticularly limited as long as it meets the aforesaid requirements. Theliquid preferably has a boiling point of 30 to 500 degrees C., morepreferably 50 to 300 degrees C. When the boiling point is lower theaforesaid upper limit, the liquid can be removed only by evaporation, sothat process steps are fewer and an amount of the liquid remaining inthe silicone composite particle is less.

Examples of the liquid to be contained in the silicone rubber particleinclude aliphatic hydrocarbons such as pentane, hexane, heptane, octane,nonane, decane, undecane, dodecane, hexadecane, octadecane, cyclohexane;aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene;alcohols such as butanol, hexanol, octanol, decanol, cyclohexanol andbenzylalcohol; halogenated hydrocarbons such as chloroform, carbontetrachloride, ethyl chloride and chlorobenzene; esters such as ethylacetate, isopropyl acetate, ethyl acetoacetate, amil acetate, isobutylisobytyrate and benzyl acetate; ethers such as ethyl ether, butyl ether,tetrahydrofuran and 1,4-dioxane; ketones such as acetone, methyl ethylketone, cyclohexanone, diaceton alcohol, methyl amyl ketone anddiisobutyl ketone.

The liquid may be an organopolysiloxane. Such an organopolysiloxane isrepresented by an average formula: R⁶ _(e) SiO_((4-e)/2). R⁶ is anunsubstituted or substituted monovalent hydrocarbon group having 1 to 30carbon atoms and e is a positive number satisfying 1<=e<=3, preferably0.5<=e<=2.3. Examples of R⁶ include an alkyl group such as a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a decyl group, a undecylgroup, a dodecyl group, a tetradecyl group, a pentadecyl group, ahexadecyl group, a heptadecyl group, an octadecyl group, a nonadecylgroup, an eicosyl group, a henicosyl group, a docosyl group, a tricosylgroup, a tetracosyl group and a triacontyl group; an aryl group such asa phenyl group, a tolyl group, and a naphthyl group; an aralkyl groupsuch as a benzyl group and a phenethyl group; an alkenyl group such as avinyl group and an allyl group; a cycloalkyl group such as a cyclopentylgroup, a cyclohexyl group and a cycloheptyl group; and those hydrocarbongroups wherein a part or all of the hydrogen atoms bonded to a carbonatom of these groups is substituted with a substituent such as a halogenatom; fluorine atom, chlorine atom, bromine atom, and iodine atom and/oran amino group, an acryloyloxy group, a methacryloyloxy group, an epoxygroup, a glycidoxy group, a mercapto group and a carboxyl group. It isindustrially preferable that 50 mole % or more of R⁶ are a methyl group.This organopolysiloxane preferably has a viscosity at 25 degrees C. of100,000 mm²/s or less, more preferably 10,000 mm²/s or less. If theviscosity is higher than the aforesaid upper limit, it is difficult toprepare particles with a narrow size distribution in the present method.The organopolysiloxane may be linear, cyclic or branched. The aforesaidviscosity is determined at 25 degrees C. with an Ostwald viscometer.

The liquid to be contained in the silicone rubber particle may be one ora combination of two or more of the aforesaid liquids. The amount of theliquid is preferably 5 to 80 parts by mass, more preferably 10 to 70parts by mass, per 100 parts by mass of the curable liquid siliconecomposition containing a liquid. That is, the amount of the liquid ispreferably 5 to 80 parts by mass, more preferably 10 to 70 parts bymass, per 100 parts by mass of the silicone rubber particle containingthe liquid. If the amount of the liquid is smaller than the aforesaidlower limit, no dent is formed on the surface of the silicone rubberparticle after removing the liquid. If the amount of the liquid islarger than the aforesaid upper limit, the rubber hardness of thesilicone rubber particle is lower, and silicone composite particlesobtained have a higher tendency for agglomeration, so that they are noteasily dispersed into primary particles and, further, a non-stickyfeeling of cosmetics decreases.

The surfactant is used as an emulsifier in order to emulsify the curableliquid silicone composition containing the afore-mentioned liquid inwater. The surfactant is not limited to any particular one and may be anonionic surfactant, an anionic surfactant, a cationic surfactant and anamphoteric surfactant.

Examples of the nonionic surfactant include a polyoxyethylene alkylether, a polyoxyethylene polyoxypropylene alkyl ether, a polyoxyethylenealkyl phenyl ether, a polyethylene glycol fatty acid ester, a sorbitanfatty acid ester, a polyoxyethylene sorbitan fatty acid ester, apolyoxyethylene sorbit fatty acid ester, a glycerin fatty acid ester, apolyoxyethylene glycerin fatty acid ester, a polyglycerin fatty acidester, a propylene glycol fatty acid ester, a polyoxyethylene castoroil, a polyoxyethylene cured castor oil, a polyoxyethylene cured castoroil fatty acid ester, a polyoxyethylene alkyl amine, a polyoxyethylenefatty acid amide, an organopolysiloxane modified with polyoxyethylene,and an organopolysiloxane modified with polyoxyethylenepolyoxypropylene.

Examples of the anionic surfactant include alkyl sulfate ester salt,polyoxyethylene alkylether sulfate ester salt, polyoxyethylenealkylphenyl ether sulfate ester salt, sulfate ester salt of aliphaticacid alkylol amide, alkyl benzene sulfur acid salt, polyoxyethylenealkylphenyl ether sulfur acid salt, alpha-olefin sulfur acid salt,alpha-sulfo aliphatic acid ester salt, alkylnaphthalene sulfur acidsalt, alkyldiphenylether disulfur acid salt, alkane sulfur acid, N-acyltaurine acid salt, dialkylsulfosuccinic acid salt,monoalkylsulfosuccinic acid salt, polyoxyethylene alkyl ethersulfosuccinic acid salt, aliphatic acid salt, polyoxyethylene alkylether carboxylic acid salt, N-acylamino acid salt, monoalkyl phosphoricacid ester salt, dialkyl phosphoric acid ester salt and polyoxyethylenealkylether phosphoric acid ester salt.

Examples of the cationic surfactant include an alkyl trimethyl ammoniumsalt, a dialkyl dimethyl ammonium salt, a polyoxyethylene alkyl dimethylammonium salt, a dipolyoxyethylene alkyl methyl ammonium salt, atripolyoxyethylene alkyl ammonium salt, an alkyl benzyl dimethylammonium salt, an alkyl pyridinium salt, a monoalkyl amine salt and amonoalkylamide amine salt.

Examples of the amphoteric surfactant include an alkyl dimethyl amineoxide, an alkyl dimethyl carboxybetaine, an alkylamide propyl dimethylcarboxybetaine, an alkyl hydroxysulfobetaine and an alkyl carboxymethylhydroxyethyl imidazolinium betaine.

These surfactants may be used singly or as a mixture of two or more. Inparticular, a nonionic surfactant is preferable because even a smallamount of it can emulsify the aforesaid liquid silicone composition intofine particles. The amount of the surfactant is preferably 0.01 to 20parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts bymass of the curable liquid silicone composition containing the aforesaidliquid. If the amount of the surfactant is too large,polyorganosilsesquioxane may not adhere to the surface of the siliconerubber particle in the present preparation method. If the amount of thesurfactant is less than the lower limit, it is difficult to obtain afine particle.

The emulsification may be conducted with a conventional emulsificationand dispersion apparatus. Examples of the emulsification and dispersionapparatus include a high-speed rotation and centrifugal emission typeagitator such as a homodisper; a high-speed rotation and shearing typeagitator such as a homomixer; a high-pressure injection-typeemulsification disperser such as a homogenizer; a colloid mill; and anultrasonic emulsifier.

The silicone rubber particle containing a liquid can be prepared byadding a catalyst to the emulsion obtained in the afore-mentionedemulsification, followed by curing. The catalyst may be theafore-mentioned platinum group metal catalyst when the curable liquidsilicone composition is of an addition reaction type. When thedispersibility of the catalyst in water is poor, it is preferable thatthe catalyst is dissolved in a surfactant and added to the emulsion. Thesurfactant may be those as described above. In particular, a nonionicsurfactant is preferable. The curing reaction may be conducted at roomtemperature. If the reaction is not complete, the curing may beconducted under heating at a temperature below 100 degrees C.

The catalyst may be added in the curable liquid silicone composition inadvance. In this case, it is better to take into consideration areactivity of the curing liquid silicone composition and a reactiontemperature and time so as not to cause curing before finishing the stepof the emulsification. Additionally, a reaction retardant may be addedin the curing liquid silicone composition.

According to the afore-mentioned method, an aqueous dispersion of asilicone rubber particle containing a liquid is obtained. This aqueousdispersion as such may be use in the subsequent step (i). If necessary,water may be further added to the aqueous dispersion. The amount ofsilicone rubber particles containing a liquid is preferably 1 to 150parts by mass, more preferably 5 to 70 parts by mass, per 100 parts bymass of water. If the amount is smaller than the lower limit, the yieldof the intended silicone composite particles tends to be poor. If theamount is larger than the upper limit, the polyorganosilsesquioxaneresin may not adhere to the surface of the silicone rubber particle and,also, aggregation and agglomeration of the particles tend to occur.

Further, a surfactant or a water-soluble polymer may be added to theaforesaid aqueous dispersion in order to control an adhesion property ofthe polyorganosilsesquioxane to the surface of the silicone rubberparticle and a size of the composite particle to be obtained.

The surfactant further added to the aqueous dispersion may be theafore-mentioned surfactant, but is not limited to particular one. Thesurfactant may be same as or different from the surfactant contained inthe aqueous dispersion of the silicone rubber particles. Two or morekinds of the surfactants may be added.

The water-soluble polymer may be a nonionic water-soluble polymer, ananionic water-soluble polymer, a cationic water-soluble polymer and anamphoteric water-soluble polymer, but is not limited to these. Theseaqueous polymers may be used singly, or in combination of two or more ofthem.

Examples of the nonionic water-soluble polymer include a copolymer ofvinylalcohol and vinyl acetate, a polymer of acrylamide, a polymer ofvinyl pyrrolidone, a copolymer of vinyl pyrrolidone and vinyl acetate,polyethyleneglycol, a polymer of isopropylacrylamide, a polymer ofmethyl vinyl ether, starch, methyl cellulose, hydroxyethyl cellulose,hydroxypropyl cellulose, guar gum and xanthan gum.

Examples of the anionic water-soluble polymer include a polymer ofsodium acrylate, a copolymer of sodium acrylate and sodium maleate, acopolymer of sodium acrylate and acrylamide, a polymer ofstyrenesulfonic acid sodium, a copolymer of polyisoprene sulfonic acidsodium and styrene, a polymer of sodium naphthalenesulfonate,carboxymethylstarch, starch phosphate, carboxymethyl cellulose, sodiumalginate, gum arabic, carrageenan, sodium chondroitin sulfate and sodiumhyaluronate.

Example of the cationic water-soluble polymer include a polymer ofdimethyl diallyl ammonium chloride, a polymer of vinyl imidazoline, apolymer of methyl vinyl imidazolium chloride, a polymer of ethylacrylate trimethyl ammonium chloride, a polymer of ethyl methacrylatetrimethyl ammonium chloride, a polymer of(3-acrylamidopropyl)trimethylammonium chloride, a polymer of(3-methacrylamidepropyl)trimethylammonium chloride, a copolymer ofepichlorohydrin and dimethylamine, a polymer of ethylene imine, aquaternary compound of polyethylene imine, a polymer of allylaminehydrochloride salt, polylysine, cationic starch, cationic cellulose,chitosan, and these substances copolymerized with a monomer containing anonionic group or an anionic group.

Examples of the amphoteric water-soluble polymer include a copolymer ofethyl acrylate trimethyl ammonium chloride, acrylic acid and acrylamide;a copolymer of ethyl methacrylate trimethyl ammonium chloride, acrylicacid and acrylamide; and Hofmann degradation product of a polymer ofacrylamide.

(i) Step of Having a Polyorganosilsesquioxane Adhered on the ParticleSurface

The present method comprises steps of subjecting organotrialkoxysilaneto hydrolysis and subsequent condensation in the presence of water, analkaline substance and a silicone rubber particle containing a liquid tothereby have a resultant polyorganosilsesquioxane adhered on the surfaceof the silicone rubber particles. The alkaline substance works as acatalyst for hydrolysis and condensation reactions of theorganotrialkoxysilane. The alkaline substance may be used singly, or twoor more of them. The alkaline substance may be added as it is or as anaqueous alkaline solution. The alkaline substance may be added before orafter the organotrialkoxysilane is added to an aqueous dispersion ofwater and silicone rubber particles containing a liquid.

The amount of the alkaline substance is such that a pH of the aqueousdispersion of water and the silicone rubber particle containing a liquidis preferably in the range of 9.0 to 13.0, more preferably 9.5 to 12.5.When the pH is in the aforesaid range, the hydrolysis and condensationreaction of organotrialkoxy silane proceeds sufficiently to thereby havea resultant polyorganosilsesquioxane adhered sufficiently to the surfaceof the silicone rubber particle.

Any alkaline substance can be use, as long as it promotes the hydrolysisand condensation reactions of organotrialkoxy silane. Examples of thealkaline substance include alkaline metal hydroxide such as potassiumhydroxide, sodium hydroxide, and lithium hydroxide; an alkaline earthmetal hydroxide such as calcium hydroxide and barium hydroxide; analkali metal carbonate such as potassium carbonate and sodium carbonate;ammonia; a tetraalkyl ammonium hydroxide such as tetramethyl ammoniumhydroxide and tetraethyl ammonium hydroxide; and an amine such asmonomethyl amine, monoethyl amine, monopropyl amine, monobutyl amine,monopentyl amine, dimethyl amine, diethyl amine, trimethyl amine,triethanol amine, and ethylene diamine. Among them, ammonia is mostpreferable because it can be easily removed from the obtained siliconerubber particle by evaporation. A commercially available aqueousammonium solution may be used.

In the step (i) of the present method, organotrialkoxysilane issubjected to a hydrolysis and condensation reactions in the presence ofwater, an alkaline substance and a silicone rubber particle containingtherein a liquid, to thereby form a polyorganosilsesquioxane. Theresultant polyorganosilsesquioxane is in a state where it adheres to thesurface of the silicone rubber particle.

An organotrialkoxysilane is represented, for example, by the formula:R⁵Si(OR⁷)₃, wherein R⁵ is as described above and R⁷ is an unsubstitutedmonovalent hydrocarbon group having 1 to 6 carbon atoms. Examples of R⁷include a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group and a hexyl group. Among these, a methyl group ispreferable in view of reactivity. In a case where it is desired tointroduce one selected from the units represented by R⁵ ₂SiO_(2/2), R⁵₃SiO_(1/2) and SiO_(4/2) into a polyorganosilsesquioxane, at least onecompound corresponding to the respective unit and represented by R⁵₂Si(OR⁷)₂, R⁵ ₃SiOR⁷ or Si(OR⁷)₄ may be added as a starting material(wherein, R⁵ and R⁶ are as defined above). In a case where R⁵Si(OR⁷)₃and at least one of R⁵ ₂Si(OR⁷)₂, R⁵ ₃SiOR⁷ and Si(OR⁷)₄ are used asstarting materials for the polyorganosilsesquioxane, the content ofR⁵Si(OR⁷)₃ is preferably 70 mole % or more, or more preferably 80 mole %or more, relative to a total mole of these starting materials. The upperlimit may near to 100 mole %.

The amount of the organotrialkoxysilane is such that the content of thepolyorganosilsesquioxane is in the range of 1 to 50 parts by mass,preferably 2 to 25 parts by mass, per 100 parts by mass of the siliconerubber particle.

The step of adding the organotrialkoxysilane is conducted preferablyunder stirring with a usual agitator such as propeller blades and plateblades.

In a case where the organotrialkoxysilane is added after an alkalinesubstance is added to an aqueous dispersion of water and a siliconerubber particle containing a liquid, the organotrialkoxysilane may beadded all at once, but preferably gradually over time. A temperatureduring this addition is preferably in the range of 0 to 60 degrees C.,more preferably 0 to 40 degree C., so that polyorganosilsesquioxaneadheres well to the surface of the silicone rubber particle containing aliquid. The stirring is continued even after adding theorganotrialkoxysilane until the hydrolysis and condensation reactions ofthe organotrialkoxysilane completes. In order to complete the hydrolysisand condensation reactions, the reaction may be carried out at roomtemperature or under heating at 40 to 100 degrees C. Further, if need,the alkaline substance is properly replenished in the reaction mixture.

In the present method, the organotrialkoxysilane may be added beforeadding an alkaline substance. In this case, it is preferred to first addthe organotrialkoxysilane to water. The organotrialkoxysilane may beadded to water all at once, or gradually over time. Alternatively, watermay be added to the organotrialkoxysilane, or water and theorganotrialkoxysilane may be put in a vessel at the same time and mixed.A temperature at which the organotrialkoxysilane is added to water isnot limited particularly, and may be, for instance, in the range of from0 to 100 degrees C. Stirring is continued until at least theorganotrialkoxysilane dissolves in water. A small amount of acid may beadded in order to promote the hydrolysis reaction.

A silicone rubber particle containing a liquid is added to the solutionobtained in the afore-mentioned step and, then, an alkaline substance isadded thereto. Then, a condensation reaction of the hydrolysate of theorganotrialkoxysilane progresses to thereby form apolyorganosilsesquioxane. The stirring is stopped or made very slowbefore polyorganosilsesquioxane is produced. If the reaction mixture isflowing at a high speed at the time when polyorganosilsesquioxane isbeing formed, the polyorganosilsesquioxane does not adhere well to thesurface of the silicone rubber particle containing a liquid. Acondensation reaction temperature is preferably 0 to 60 degrees C., morepreferably 0 to 40 degrees C. When the temperature is in the aforesaidrange, the polyorganosilsesquioxane adheres well to the surface of thesilicone rubber particle containing a liquid. The reaction solution ispreferably left standing or stirred at a very slow speed untilpolyorganosilsesquioxane is produced, and adheres to the surface of thesilicone rubber particle. The time of standing is preferably 10 minutesto 24 hours. After that, an alkaline substance may be added thereto, thereaction mixture may be heated at 40 to 100 degrees C. or usual stirringis further conducted, in order to complete the condensation.

(ii) Step of Removing the Liquid

The present method contains a step of removing the liquid contained inthe silicone rubber particle and water by evaporation afterpolyorganosilsesquioxane adheres to the surface of the silicone rubberparticle contained a liquid. In this step, the silicone rubber particleshrinks to form dents on its surface.

The step of removing the liquid contained in the silicone rubberparticle may be conducted according to any conventional manner. In acase where the liquid has a high boiling point so that it cannot beremoved by volatilization, or where the evaporation conducts at a lowtemperature, the silicone rubber particle is first washed with a solventhaving a low boiling point. The solvent is not limited to any particularone and may be such having a low boiling point among the solventsdescribed above for a liquid to be contained in a silicone rubberparticle. One solvent or a mixture of two or more may be used. Beforewashing, the dispersion may be concentrated by, for instance, thermaldehydration, separation by filtration, centrifugalization ordecantation. The dispersion may be dehydrated by heating and, thencrushed into powder. Then, a solvent is added to the dispersion,concentrate or powder, and stirred with a usual agitator havingpropeller blades or flat-plate blades and, then, a solid and a liquidare separated by, for instance, filtration, centrifugalization ordecantation. By repeating this step, the liquid contained in thesilicone rubber particle is replaced with the solvent having a lowboiling point.

The liquid contained in the silicone rubber particle or the solventexchanged with the liquid in the step of washing, and water may beremoved by heating under normal pressure or reduced pressure such asheating the dispersion left standing, heating the dispersion beingstirred to flow, spraying the dispersion in hot air stream in a spraydryer to disperse, or using a fluid heating medium. As a pre-treatmentbefore the afore-mentioned step, the dispersion may be concentrated asdescribed above or, if necessary, the dispersion may be washed withwater or water-soluble alcohol.

If the silicone composite particles obtained after evaporating andremoving the liquid and water is in an agglomerated state, theagglomerate may be crushed by a crusher such as a jet mill, a ball milland a hammer mill.

EXAMPLES

The present invention will be explained below in further detail withreference to a series of the Examples and the Comparative Examples,though the present invention is in no way limited by these Examples. Inthe following descriptions, a viscosity is a dynamic viscositydetermined at 25 degrees C. with an Ostwald viscometer, and percentage,“%”, in a concentration and a content, is by mass.

Example 1 Preparation of an Aqueous Dispersion of a Silicone RubberParticle Containing Therein Dimethylpolysiloxane

In a one-liter glass beaker, put were 264 g of a methyl vinylpolysiloxane which is represented by the following formula (1):

and has a dynamic viscosity of 600 mm²/s; 11 g of a methyl hydrogenpolysiloxane which is represented by the following formula (2):

and has a dynamic viscosity of 30 mm²/s, wherein this amount of themethyl hydrogen polysiloxane gives the number of the hydrosilyl groupsof 1.18, per olefinic unsaturated group of the methyl vinylpolysiloxane;and 225 g of a dimethylpolysiloxane which is represented by thefollowing formula (3):

and has a dynamic viscosity of 2 mm²/s and a boiling point of 230degrees C., wherein this amount of the dimethylpolysiloxane gives 45parts by mass of the dimethylpolysiloxane, per 100 parts by mass of thesilicone rubber particle containing the dimethylpolysiloxane, andstirred with a homomixer at 2,000 rpm to be dissolved each other.Subsequently, 0.8 g of polyoxyethylene lauryl ether having 9 unitsderived from ethylene oxide, and 100 g of water were added thereto and,then, stirred with a homomixer at 8,000 rpm, whereby an oil-in-waterstate was obtained and thickening was observed. Then, the stirring wascontinued for further 15 minutes. Subsequently, 398 g of water was addedthereto with stirring at 2,000 rpm to obtain a homogenous whiteemulsion. This emulsion was taken in a one-liter glass flask equippedwith a stirrer having anchor type stirring blades, the temperaturethereof was adjusted to 20-25 degrees C., to which then, added withstirring was a solution consisting of 0.5 g of a solution ofchloroplatinic acid-olefin complex in toluene, containing 0.5 mass % ofplatinum, and 1 g of polyoxyethylene lauryl ether having 9 units derivedfrom ethylene oxide. The resulting mixture was stirred for 12 hours atthe same temperature to obtain an aqueous dispersion of silicone rubberparticles containing therein the dimethylpolysiloxane.

The shape of the silicone rubber particles containing therein thedimethylpolysiloxane in the aqueous dispersion thus obtained wasspherical under observation with an optical microscope and thevolume-average particle diameter thereof was 12 μm, as determined with aparticle size distribution measurement instrument using an electricresistance method, Multisizer 3, manufactured by Beckman Coulter, Inc.

Hardness of the silicone rubber particle was determined according to thefollowing method.

The methyl vinyl polysiloxane represented by the afore-mentioned formula(1), the methyl hydrogen polysiloxane represented by the afore-mentionedformula (2), the dimethylpolysiloxane represented by the afore-mentionedformula (3) and the solution of chloroplatinic acid-olefin complex intoluene, containing 0.5 mass % of platinum, were mixed in theafore-mentioned ratio, poured into an aluminum petri dish up to a depthof 10 mm and allowed to stand at 25 degrees C. for 24 hours. Then, themixture was heated in a thermostat at 50 degrees C. for one hour toobtain a silicone rubber containing the dimethylpolysiloxane. Thesilicone rubber thus obtained was removed from the aluminum petri dishand dried in a vaccum dryer at 3×10⁻³ Pa and 100 degrees C. to removethe dimethylpolysiloxane from the silicone rubber to obtain a non-stickysilicone rubber.

Hardness of the silicone rubber was 15, as determined with a durometer Ahardness meter.

Preparation of a Silicone Composite Particle

In a two-liter glass flask equipped with a stirrer having anchor typestirring blades, transferred was 300 g of the aqueous dispersion of thesilicone rubber particles containing the dimethylpolysiloxane obtainedin the afore-mentioned procedures, to which then added were 661 g ofwater, 19 g of an aqueous 28% ammonium solution and 1 g of an aqueous40% solution of a dimethyl diallyl ammonium chloride polymer, tradename: ME Polymer H40W, manufactured by Toho Chemical Industry Co., Ltd.At this point of time, a pH of the resulting mixture was 11.8. Thetemperature of the resulting mixture was adjusted to 5-10 degrees C.and, then, 19 g of methyltrimethoxysilane was gradually added over 20minutes, wherein this amount would give 11.3 parts by mass of apolymethylsilsesquioxane after the hydrolysis and condensationreactions, per 100 parts by mass of the silicone rubber particles. Then,the stirring was continued for further one hour while maintaining thesolution temperature at 5-10 degrees C. Subsequently, the mixture washeated to 55-60 degrees C. and stirred for further one hour whilemaintaining at this temperature to complete the hydrolysis andcondensation reactions of methyltrimethoxysilane.

The aqueous dispersion thus obtained was dehydrated with a press filterto have a water content of approximately 30%. This was transferred to atwo-liter glass flask equipped with a stirrer having anchor typestirring blades, 1000 g of water was added thereto, stirred for 30minutes and, then, dehydration was conducted with a press filter. Thiswas transferred again to a two-liter glass flask equipped with a stirrerhaving anchor type stirring blades, 1000 g of water was added thereto,stirred for 30 minutes and, then, dehydration was conducted with a pressfilter. The resultant dehydrated matter was dried in a vacuum dryer at3×10⁻³ Pa and 100 degrees C. to remove the dimethylpolysiloxanecontained in the silicone rubber particles and water. The dried matterthus obtained was crushed with a jet mill to obtain fluid siliconecomposite particles.

The silicone composite particles thus obtained were dispersed in waterwith a surfactant. The volume-average particle diameter was 11 μm, asdetermined with a particle size distribution measurement instrumentusing an electric resistance method, Multisizer 3, manufactured byBeckman Coulter, Inc. Further, it was confirmed under observation withan electron microscope that the silicone rubber particles had pluralpolyhedral dents on their surfaces. It was further confirmed thatparticulate polymethylsilsesquioxane having a diameter of about 100 nmadhered on the surface of the silicone particles. FIG. 1 is an electronmicroscope image of the surface of this silicone composite particle.

Example 2 Preparation of an Aqueous Dispersion of Silicone RubberParticles Containing Isododecane

In a one-liter glass beaker, put were 172 g of a methyl vinylpolysiloxane which is represented by the afore-mentioned formula (1) andhas a dynamic viscosity of 600 mm²/s; 7 g of a methyl hydrogenpolysiloxane which is represented by the afore-mentioned formula (2) andhas a dynamic viscosity of 30 mm²/s, wherein this amount of the methylhydrogen polysiloxane gives the number of the hydrosilyl groups of 1.15,per olefinic unsaturated group of the methyl vinyl polysiloxane; and 341g of isododecane, wherein the amount of the isododecane gives 66 partsby mass of the isododecane, per 100 parts by mass of the silicone rubberparticles containing the isododecane, and stirred with a homomixer at2,000 rpm to be dissolved each other. Subsequently, 2 g ofpolyoxyethylene lauryl ether having 9 units derived from ethylene oxide,and 40 g of water were added thereto and, then, stirred with a homomixerat 8,000 rpm, whereby an oil-in-water state was obtained and thickeningwas observed. The stirring was continued for further 15 minutes.Subsequently, 437 g of water was added thereto with stirring at 2,000rpm to obtain a homogenous white emulsion. This emulsion was taken in aone-liter glass flask equipped with a stirrer having anchor typestirring blades, the temperature thereof was adjusted to 20-25 degreesC., to which then added with stirring was a solution consisting of 0.3 gof a solution of chloroplatinic acid-olefin complex in toluene,containing 0.5 mass % of platinum, and 0.5 g of polyoxyethylene laurylether having 9 units derived from ethylene oxide. The resulting mixturewas stirred for 12 hours at the same temperature to obtain an aqueousdispersion of silicone rubber particles containing isododecane.

The shape of the silicone rubber particles containing isododecane in theaqueous dispersion thus obtained was spherical under observation with anoptical microscope and the volume-average particle diameter thereof was5 μm, as determined with a particle size distribution measurementinstrument using an electric resistance method, Multisizer 3,manufactured by Beckman Coulter, Inc.

Hardness of the silicone rubber particle was determined according to thefollowing method.

The methyl vinyl polysiloxane represented by the afore-mentioned formula(1), the methyl hydrogen polysiloxane represented by the afore-mentionedformula (2), isododecane and the solution of chloroplatinic acid-olefincomplex in toluene, containing 0.5 mass % of platinum, were mixed in theafore-mentioned ratio, poured into an aluminum petri dish up to a depthof 10 mm and allowed to stand at 25 degrees C. for 24 hours. Then, themixture was heated in a thermostat at 50 degrees C. for one hour toobtain a silicone rubber containing isododecane. The silicone rubberthus obtained was removed from the aluminum petri dish and dried in avacuum dryer at 3×10⁻³ Pa and 100 degrees C. to remove isododecane fromthe silicone rubber to obtain a non-sticky silicone rubber.

Hardness of the silicone rubber was 11, as determined with a durometer Ahardness meter.

Preparation of a Silicone Composite Particle

In a two-liter glass flask equipped with a stirrer having anchor typestirring blades, transferred was 288 g of the aqueous dispersion of thesilicone rubber particles containing isododecane obtained in theafore-mentioned procedures, to which then added were 673 g of water, 19g of an aqueous 28% ammonium solution and 1 g of an aqueous 40% solutionof a dimethyl diallyl ammonium chloride polymer, trade name: ME PolymerH40W, manufactured by Toho Chemical Industry Co., Ltd. At this point oftime, a pH of the resulting mixture was 11.8. The temperature of theresulting mixture was adjusted to 5-10 degrees C. and, then, 19 g ofmethyltrimethoxysilane was gradually added over 20 minutes, wherein thisamount would give 18.2 parts by mass of a polymethylsilsesquioxane afterhydrolysis and condensation reactions, per 100 parts by mass of thesilicone rubber particles. Then, the stirring was continued for furtherone hour while maintaining the mixture temperature at 5-10 degrees C.Subsequently, the mixture was heated to 55-60 degrees C. and stirred forfurther one hour while maintaining this temperature, to complete thehydrolysis and condensation reactions of methyltrimethoxysilane.

The aqueous dispersion thus obtained was dehydrated with a press filterto have a water content of approximately 30%. This was transferred to atwo-liter glass flask equipped with a stirrer having anchor typestirring blades, 1000 g of water was added thereto, stirred for 30minutes and, then, dehydrated with a press filter. This was transferredagain to a two-liter glass flask equipped with a stirrer having anchortype stirring blades, 1000 g of water was added thereto, stirred for 30minutes and, then, dehydrated with a press filter. The resultantdehydrated matter was dried in a vacuum dryer at 3×10⁻³ Pa and 100degrees C. to remove isododecane remaining in the silicone rubberparticles and water. The dried matter thus obtained was crushed with ajet mill to obtain fluid silicone composite particles.

The silicone composite particles thus obtained were dispersed in waterwith a surfactant. The volume-average particle diameter was 3 μm, asdetermined with a particle size distribution measurement instrumentusing an electric resistance method, Multisizer 3, manufactured byBeckman Coulter, Inc. Further, it was confirmed under observation withan electron microscope that the silicone rubber particles had about 4 to10 tetrahedral or pentahedral dents on the surface of each particle. Itwas further confirmed that particulate polymethylsilsesquioxane having adiameter of about 80 nm adhered on the surfaces. FIG. 2 is an electronmicroscope image of the surface of this silicone composite particle.

Comparative Example 1 Preparation of an Aqueous Dispersion of SiliconeRubber Particles Containing No Liquid

In a one-liter glass beaker, put were 442 g of a methyl vinylpolysiloxane which is represented by the afore-mentioned formula (1) andhas a dynamic viscosity of 600 mm²/s and 58 g of a methyl hydrogenpolysiloxane which is represented by the following formula (4):

and has a dynamic viscosity of 28 mm²/s, wherein the amount of methylhydrogen polysiloxane gives the number of the hydrosilyl groups of 1.14,per olefinic unsaturated group of the methyl vinyl polysiloxane, andstirred with a homomixer at 2,000 rpm to be dissolved each other.Subsequently, 0.8 g of polyoxyethylene lauryl ether having 9 unitsderived from ethylene oxide and 100 g of water were added thereto and,then, stirred with a homomixer at 8,000 rpm, whereby an oil-in-waterstate was obtained and thickening was observed. Then, the stirring wascontinued for further 15 minutes. Subsequently, 398 g of water was addedthereto with stirring at 2,000 rpm to obtain a homogenous whiteemulsion. This emulsion was taken in a one-liter glass flask equippedwith a stirrer having anchor type stirring blades, and the temperaturethereof was adjusted to 20-25 degrees C., to which, then, added withstirring was a solution consisting of 0.8 g of a solution ofchloroplatinic acid-olefin complex in toluene, containing 0.5 mass % ofplatinum, and 1 g of polyoxyethylene lauryl ether having 9 units derivedfrom ethylene oxide. The resulting mixture was stirred for 12 hours atthe same temperature to obtain an aqueous dispersion of silicone rubberparticles which did not contain any liquid.

The shape of the silicone rubber particles in the aqueous dispersionthus obtained was spherical under observation with an optical microscopeand the volume-average particle diameter thereof was 13 μm, asdetermined with a particle size distribution measurement instrumentusing an electric resistance method, Multisizer 3, manufactured byBeckman Coulter, Inc.

Hardness of the silicone rubber particle was determined according to thefollowing method.

The methyl vinyl polysiloxane represented by the afore-mentioned formula(1), the methyl hydrogen polysiloxane represented by the afore-mentionedformula (4) and a solution of chloroplatinic acid-olefin complex intoluene, containing 0.5 mass % of platinum, were mixed in theafore-mentioned ratio, poured into an aluminum petri dish up to a depthof 10 mm and allowed to stand at 25 degrees C. for 24 hours. Then, themixture was heated in a thermostat at 50 degrees C. for one hour toobtain a non-sticky silicone rubber. Hardness of the silicone rubber was13, as determined with a durometer A hardness meter.

Preparation of a Silicone Composite Particle

In a two-liter glass flask equipped with a stirrer having anchor typestirring blades, transferred was 300 g of the aqueous dispersion of thesilicone rubber particles obtained in the afore-mentioned procedures, towhich then added were 661 g of water and 19 g of an aqueous 28% ammoniumsolution. At this point of time, a pH of the resulting mixture was 11.8.The temperature of the resulting mixture was adjusted to 5-10 degrees C.and, then, 20 g of methyltrimethoxysilane was gradually added over 20minutes, wherein this amount was would give 6.6 parts by mass of apolymethylsilsesquioxane after the hydrolysis and condensationreactions, per 100 parts by mass of the silicone rubber mixture. Then,the stirring was continued for further one hour while maintaining themixture temperature at 5-10 degrees C. Subsequently, the mixture washeated to 55-60 degrees C. and stirred for further one hour whilemaintaining this temperature, to complete the hydrolysis andcondensation reactions of methyltrimethoxysilane.

The aqueous dispersion thus obtained was dehydrated with a press filterto a water content of approximately 30%. This was transferred to atwo-liter glass flask equipped with a stirrer having anchor typestirring blades, 1000 g of water was added thereto, stirred for 30minutes and, then, dehydrated was conducted with a press filter. Thiswas transferred again to a two-liter glass flask equipped with a stirrerhaving anchor type stirring blades, 1000 g of water was added thereto,stirred for 30 minutes and, then, dehydrated with a press filter. Theresultant dehydrated matter was dried in a vaccum dryer at 105 degreesC. to remove water. The dried matter thus obtained was crushed with ajet mill to obtain fluid silicone composite particles.

The silicone composite particles thus obtained were dispersed in waterwith a surfactant. The volume-average particle diameter was 13 μm, asdetermined with a particle size distribution measurement instrumentusing an electric resistance method, Multisizer 3, manufactured byBeckman Coulter, Inc. Further, it was confirmed under observation withan electron microscope that the surface of the silicone rubber particleswas covered with particulate polymethylsilsesquioxane having a diameterof about 100 nm, but had no dent. FIG. 3 is an electron microscope imageof the surface of this silicone composite particle.

Comparative Example 2

The aqueous dispersion of the silicone rubber particles obtained inExample 1, which contained dimethylpolysiloxane, was dried with a spraydryer to remove water and obtain powder. The resultant powder was driedin a vacuum dryer at 3×10⁻³ Pa and 100 degrees C. to removedimethylpolysiloxane from the silicone rubber particles to obtainsilicone rubber particles. It was confirmed under observation with anelectron microscope that the silicone rubber particles were sphericalparticles having no dent.

Comparative Example 3 Preparation of an Aqueous Dispersion of a SiliconeRubber Particle Containing Dimethylpolysiloxane and Having High Hardness

In a one-liter glass beaker, put were 360 g of a methyl vinylpolysiloxane which is represented by the following formula (5):

and has a dynamic viscosity of 100 mm²/s; 40 g of a methyl hydrogenpolysiloxane which is represented by the afore-mentioned formula (2) andhas a dynamic viscosity of 30 mm²/s, wherein the amount of the methylhydrogen polysiloxane gives the number of the hydrosilyl groups of 1.16,per olefinic unsaturated group of the methyl vinyl polysiloxane; and 100g of a dimethylpolysiloxane which is represented by the afore-mentionedformula (3) and has a dynamic viscosity of 2 mm²/s and a boiling pointof 230 degrees C., wherein this amount of the dimethylpolysiloxane gives20 parts by mass of the dimethylpolysiloxane, per 100 parts by mass ofsilicone rubber particles containing the dimethylpolysiloxane, andstirred with a homomixer at 2,000 rpm to be dissolved each other.Subsequently, 0.8 g of polyoxyethylene lauryl ether having 9 unitsderived from ethylene oxide and 100 g of water were added thereto and,then, stirred with a homomixer at 8,000 rpm, whereby an oil-in-waterstate was obtained and thickening was observed. Then, the stirring wascontinued for further 15 minutes. Subsequently, 398 g of water was addedthereto with stirring at 2,000 rpm to obtain a homogenous whiteemulsion. This emulsion was taken in a one-liter glass flask equippedwith a stirrer having anchor type stirring blades, and the temperaturethereof was adjusted to 20-25 degrees C., to which then, added withstirring was a solution consisting of 0.8 g of a solution ofchloroplatinic acid-olefin complex in toluene, containing 0.5 mass % ofplatinum, and 1 g of polyoxyethylene lauryl ether having 9 units derivedfrom of ethylene oxide. The resulting mixture was stirred for 12 hoursat the same temperature to obtain an aqueous dispersion of siliconerubber particles containing dimethylpolysiloxane.

The shape of the silicone rubber particles in the aqueous dispersionthus obtained was spherical under observation with an optical microscopeand the volume-average particle diameter thereof was 13 μm, asdetermined with a particle size distribution measurement instrumentusing an electric resistance method, Multisizer 3, manufactured byBeckman Coulter, Inc.

Hardness of the silicone rubber particle was determined according to thefollowing method.

The methyl vinyl polysiloxane represented by the afore-mentioned formula(5), the methyl hydrogen polysiloxane represented by the afore-mentionedformula (2), the dimethylpolysiloxane represented by the afore-mentionedformula (3) and a solution of chloroplatinic acid-olefin complex intoluene, containing 0.5 mass % of platinum, were mixed in theafore-mentioned ratio, poured into an aluminum petri dish up to a depthof 10 mm and allowed to stand at 25 degrees C. for 24 hours. Then, themixture was heated in a thermostat at 50 degrees C. for one hour toobtain a silicone rubber containing the dimethylpolysiloxane. Thesilicone rubber containing the dimethylpolysiloxane thus obtained wasremoved from the aluminum petri dish and dried in a vacuum dryer at3×10⁻³ Pa and 100 degrees C. to remove the dimethylpolysiloxane from thesilicone rubber and obtain non-sticky silicone rubber.

Hardness of the silicone rubber was 38, as determined with a durometer Ahardness meter.

Preparation of a Silicone Composite Particle

In a two-liter glass flask equipped with a stirrer having anchor typestirring blades, transferred was 300 g of the aqueous dispersion of thesilicone rubber particles containing the dimethylpolysiloxane obtainedin the afore-mentioned procedures, to which then added were 661 g ofwater, 19 g of an aqueous 28% ammonium solution, and 1 g of an aqueous40% solution of dimethyl diallyl ammonium chloride polymer, trade name:ME Polymer H40W, manufactured by Toho Chemical Industry Co., Ltd. Atthis point of time, a pH of the resulting mixture was 11.8. Thetemperature of the resulting mixture was adjusted to 5-10 degrees C.and, then, 19 g of methyltrimethoxysilane was gradually added over 20minutes, wherein this amount would give 7.8 parts by mass of thepolymethylsilsesquioxane after the hydrolysis and condensationreactions, per 100 parts by mass of the silicone rubber particle. Then,the stirring was continued for further one hour while maintaining themixture temperature at 5-10 degrees C. Subsequently, the mixture washeated to 55-60 degrees C. and stirred for further one hour whilemaintaining this temperature, to complete the hydrolysis andcondensation reactions of methyltrimethoxysilane.

The aqueous dispersion thus obtained was dehydrated with a press filterto a water content of approximately 30%. This was transferred to atwo-liter glass flask equipped with a stirrer having anchor typestirring blades, 1000 g of water was added thereto, stirred for 30minutes and, then, dehydrated with a press filter. This was transferredagain to a two-liter glass flask equipped with a stirrer having anchortype stirring blades, 1000 g of water was added thereto, stirred for 30minutes and, then, dehydrated with a press filter. The resultantdehydrated matter was dried in a vacuum dryer at 3×10⁻³ Pa and 100degrees C. to remove the dimethylpolysiloxane remaining in the siliconerubber particles and water. The dried matter thus obtained was crushedwith a jet mill to obtain fluid silicone composite particles.

The silicone composite particles thus obtained were dispersed in waterwith a surfactant. The volume-average particle diameter was 12 μm, asdetermined with a particle size distribution measurement instrumentusing an electric resistance method, Multisizer 3, manufactured byBeckman Coulter, Inc. Further, it was confirmed under observation withan electron microscope that the surface of the silicone rubber particleswas covered with particulate polymethylsilsesquioxane having a diameterof about 80 nm and that the silicone composite particles were sphericalwith no dent.

INDUSTRIAL APPLICABILITY

The present silicone composite particle is expected to provide a higherlight scattering effect and, therefore, is expected to be useful forcosmetics.

1. A silicone composite particle composed of a silicone rubber particle and a polyorganosilsesquioxane, wherein the silicone rubber particle has plural dents on its surface and said polyorganosilsesquioxane adheres to the surface of the silicone rubber particle.
 2. The silicone composite particle according to claim 1, wherein the silicone rubber particle has plural polyhedral dents on the surface.
 3. The silicone composite particle according to claim 1, wherein the silicone rubber particle has a volume-average particle diameter of 0.5 to 100 μm.
 4. The silicone composite particle according to claim 1, wherein the polyorganosilsesquioxane is spherical and has a particle diameter of 10 to 400 nm.
 5. The silicone composite particle according to claim 1, wherein an amount of the polyorganosilsesquioxane is 1 to 50 parts by mass, per 100 parts by mass of the silicone rubber particle.
 6. The silicone composite particle according to claim 1, wherein the silicone rubber particle has a rubber hardness of 5 to 35 as determined with a type A durometer, according to the Japanese Industrial Standards (JIS) K
 6253. 7. A method for preparing the silicone composite particle according to claim 1, wherein the method comprises steps of subjecting organotrialkoxysilane to hydrolysis and condensation reactions in the presence of water, an alkaline substance, and a silicone rubber particle containing therein a liquid to thereby have a resultant polyorganosilsesquioxane adhered to the surface of the silicone rubber particle, and subsequently removing the liquid.
 8. The method according to claim 7, wherein said liquid is dissolved in a curable liquid silicone composition to form a solution, adding a surfactant and water to the obtained solution, emulsifying them, and curing the curable liquid silicone composition in the presence of a catalyst to thereby have said liquid contained in a resultant silicone rubber particle.
 9. The method according to claim 7, wherein the liquid is one or more selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, halogenated hydrocarbons, esters, ethers, ketones and organopolysiloxanes.
 10. The method according to claim 7, wherein an amount of the liquid is 5 to 80 parts by mass, per 100 parts by mass of the silicone rubber particle containing therein the liquid. 